Abstract

Most breast cancer deaths are caused by metastasis and treatment options beyond radiation and cytotoxic drugs are urgently needed. This study reanalyzed existing data from three genome-wide association studies (GWAS) using a novel computational biostatistics approach (muGWAS), which had been validated in studies of 600-2000 subjects in epilepsy and autism. MuGWAS jointly analyzes several neighboring single nucleotide polymorphisms while incorporating knowledge about genetics of heritable diseases into the statistical method and about GWAS into the rules for determining adaptive genome-wide significance.
Results from three independent GWAS of 1000-2000 subjects each, which were made available under the National Institute of Health's "Up For A Challenge" (U4C) project, not only confirmed cell-cycle control and receptor/AKT signaling, but, for the first time in breast cancer GWAS, also consistently identified many endo-/exocytosis (EEC) genes, most of which had already been observed in functional and expression studies of breast cancer. In particular, the findings include genes that translocate (ATP8A1, ATP8B1, ANO4, ABCA1) and metabolize (AGPAT3, AGPAT4, DGKQ, LPPR1) phospholipids entering the phosphatidylinositol cycle, which controls EEC. These novel findings suggest scavenging phospholipids via alpha-cyclodextrin (aCD) as a novel intervention to control packaging of exosomes (which prepare distant microenvironment for organ-specific metastases) and endocytosis of b1 integrins (which are required for spread of metastatic phenotype and mesenchymal migration of tumor cells).
Beta-cyclodextrin (bCD) had already been shown to be effective in in vitro and animal studies of breast cancer, but exhibits cholesterol-related ototoxicity. The smaller a;CD also scavenges phospholipids, but cannot fit cholesterol. An in-vitro study presented here confirms hydroxypropyl (HP)-aCD to be twice as effective as bCD against migration of human cells of both receptor negative and estrogen-receptor positive breast cancer.
If the previous successful animal studies with bCDs are replicated with the safer and more effective aCDs, clinical trials of aCDs are warranted in women with triple-negative breast cancer, who have few treatment options and poor prognosis.

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